Organic leachables from polymer-based dental filling materials

Results are reported from a study on the in vitro separation and identification of leachables from three different polymer-based dental filling materials by using a combined method of gas chromatography and mass spectrometry. The median number of separable organic leachables in these materials was between 14 and 22. Of these organic leachables the following were identified and quantified: DL-camphorquinone, 4-dimethylaminobenzoic acid ethyl ester (DMABEE), drometrizole, 1,7,7-trimethylbicyclo[2,2,1]heptane, 2,2-dimethoxy[1,2] diphenyletanone (DMBZ), ethyleneglycol dimethacrylate (EGDMA), and triethyleneglycol dimethacrylate (TEGDMA). Three of the leachables have previously been shown to provoke allergy. The range of log P(ow) values (representing the lipophilicity of these compounds) varied between 1.09 and 4.20. By multivariate data analysis, selected leachables from the tested materials were shown to separate into characteristic patterns. The results contribute to a characterization of potential hazardous compounds in polymer-based dental filling materials.     

Effect of three-dimensional valve shape on the hemodynamics of aortic stenosis: three-dimensional echocardiographic stereolithography and patient studies

OBJECTIVES: This study tested the hypothesis that the impact of a stenotic aortic valve depends not only on the cross-sectional area of its limiting orifice but also on three-dimensional (3D) valve geometry. BACKGROUND: Valve shape can potentially affect the hemodynamic impact of aortic stenosis by altering the ratio of effective to anatomic orifice area (the coefficient of orifice contraction [Cc]). For a given flow rate and anatomic area, a lower Cc increases velocity and pressure gradient. This effect has been recognized in mitral stenosis but assumed to be absent in aortic stenosis (constant Cc of 1 in the Gorlin equation). METHODS: In order to study this effect with actual valve shapes in patients, 3D echocardiography was used to reconstruct a typical spectrum of stenotic aortic valve geometrics from doming to flat. Three different shapes were reproduced as actual models by stereolithography (computerized laser polymerization) with orifice areas of 0.5, 0.75, and 1.0 cm(2) (total of nine valves) and studied with physiologic flows. To determine whether valve shape actually influences hemodynamics in the clinical setting, we also related Cc (= continuity/planimeter areas) to stenotic aortic valve shape in 35 patients with high-quality echocardiograms. RESULTS: In the patient-derived 3D models, Cc varied prominently with valve shape, and was largest for long, tapered domes that allow more gradual flow convergence compared with more steeply converging flat valves (0.85 to 0.90 vs. 0.71 to 0.76). These variations translated into differences of up to 40% in pressure drop for the same anatomic area and flow rate, with corresponding variations in Gorlin (effective) area relative to anatomic values. In patients, Cc was significantly lower for flat versus doming bicuspid valves (0.73 +/- 0.14 vs. 0.94 +/- 0.14, p < 0.0001) with 40 +/- 5% higher gradients (p < 0.0001). CONCLUSIONS: Three-dimensional valve shape is an important determinant of pressure loss in patients with aortic stenosis, with smaller effective areas and higher pressure gradients for flatter valves. This effect can translate into clinically important differences between planimeter and effective valve areas (continuity or Gorlin). Therefore, valve shape provides additional information beyond the planimeter orifice area in determining the impact of valvular aortic stenosis on patient hemodynamics.     

Long-term influence of diet and/or omega-3 fatty acids on matrix metalloproteinase-9 and pregnancy-associated plasma protein-A in men at high risk of coronary heart disease

BACKGROUND: Matrix metalloproteinases (MMPs) are important in the atherosclerotic process. The relationship between MMPs and traditional risk factors for cardiovascular disease (CVD) and any influence of lifestyle changes are largely unknown. OBJECTIVES: In a factorial design, we studied the effects of 3 years of dietary counselling and/or n-3 PUFA supplementation (2.4 g/d) on the levels of MMP-9, tissue inhibitor of metalloproteinase (TIMP-1) and pregnancy-associated plasma protein (PAPP-A) in a population of elderly men at high risk of CVD (n = 563, age 70+/-6 years). We further explored the association between these markers and different disease entities, carotid intima media thickness (IMT) and traditional risk factors for CVD. RESULTS: Smokers had significantly higher levels of MMP-9 (p<0.0001), and TIMP-1 levels were lower in subjects with previous AMI (p = 0.021). MMP-9 was significantly correlated with LDL-C and inversely with HDL-C (both p<0.0001). There were no significant correlations between the measured variables and IMT. Significant reductions in MMP-9 and PAPP-A levels after 36 months were found in all study groups, however, with no between-group differences. CONCLUSIONS: The elevated levels of MMP-9 in smokers and the reduced levels of TIMP-1 in patients with previous AMI reflect an importance of MMPs in the development of CVD. Intervention with diet and/or n-3 PUFA supplementation did not influence the levels of MMP-9, TIMP-1 or PAPP-A in the present population.     

Dental cementum apposition as an indicator of age

The purposes of the present investigation were to examine various ways of measuring cementum thickness, to study its relationship with age, and to consider what contribution this factor might offer in methods for age estimation. The amount of dental cementum apposition was studied in 1000 teeth, excluding molars, from a Caucasian population. Cementum thickness was estimated according to the scoring methods suggested by Gustafson and by Johanson. In addition, the width of the cementum was measured at the apex and also at approximately one third of the root length from the apex. Statistical analyses using the SPSS package in a Cyber computer indicated a symmetric left/right distribution of cementum thickness. The sum of the cementum thickness on vestibular and lingual surfaces, measured at one third of the root length from the apex, showed the strongest correlation with age (r = 0.40 to 0.65). A reduced rate of cementum apposition was observed in the elderly. Also, maxillary teeth had more cementum on the lingual than on the vestibular surfaces. A tendency was noted for less cementum to occur in women than in men and on teeth removed from deceased persons or extracted for pathologic reasons. Correlation coefficients indicated that, for at least some types of teeth, the cementum thickness might give a significant contribution to statistical methods of age assessment.     

Clinical implications of red blood cell and platelet storage lesions: an overview.

Both red blood cells and platelets undergo lesions upon storage which affect their function and possibly their clinical outcome. Some of these lesions are reversible, others not. Improved additive solutions and leukocyte depletion can delay the appearance of storage lesions. In addition, cellular apoptosis leads to numerous mitochondrial and surface changes during storage which have the potential to induce immune suppression by tuning down the innate immune system. This overview highlights some laboratory and clinical aspects of red cell and platelet storage lesions.     

Bone induction by composites of bioresorbable carriers and demineralized bone in rats: A comparative study of fibrin-collagen paste, fibrin sealant, and polyorthoester with gentamicin

Host tissue response and heterotopic osteoinduction by composites of demineralized bone matrix and three different substances used as bioresorbable carriers implanted in the abdominal muscles were evaluated by strontium 85 uptake and histology 4 weeks postoperatively in 60 male Wistar rats. Both fibrin-collagen paste and fibrin sealant inhibited bone induction and produced a chronic inflammation; part of the fibrin-collagen paste was still present at 4 weeks. Polyorthoester with gentamicin was almost completely absorbed, induced minimal tissue reaction, and did not inhibit osteoinduction.     

The effect of a composite of polyorthoester and demineralized bone on the healing of large segmental defects of the radius in rats.

The effect of a composite of demineralized bone mixed with polyorthoester on the healing of large segmental defects in the rat radius was studied. Sixty male Wistar rats were divided into four groups, A through D, and an osteoperiosteal diaphyseal defect of 50 per cent of the length of the bone was made in the right radius of each rat. In Group A, the defect was filled with polyorthoester and demineralized bone; in Group B, demineralized bone; and in Group C, polyorthoester. No material was implanted in the defects in the Group-D rats. The rats were killed fifty days postoperatively. The formation of bone in the defects was quantified with computer-assisted measurements of the area on radiographs. The host-tissue response was evaluated with light microscopy. Defects that had been filled with the composite of polyorthoester and demineralized bone or with demineralized bone alone showed regeneration of bone corresponding to 93.6 and 77.6 per cent of the area of the defect, respectively. Defects that had no implant or that had been filled with polyorthoester alone showed significantly less formation of bone. No inflammation was seen with light microscopy, and only traces of the polyorthoester could be detected in the defects that had been filled with the composite or with polyorthoester alone.     

Effects of acetylsalicylic acid on intramuscular bone matrix implants and composite grafts in rats

Antigen-extracted, autolyzed, demineralized bone matrix and bone matrix combined with isogeneic bone marrow (i.e., a composite graft) were placed in the musculature of young male rats. The influence of acetylsalicylic acid (ASA) on the osteogenic potential of these bone-inducing materials was studied during an 18-day period. ASA (150 mg/kg/12 h) was used to obtain anti-inflammatory serum levels comparable with those in humans. Resorption of the implanted matrix and new formation of bone were quantified using collagen- and mineral-tracing radioisotopes and collagen and calcium analyses. The matrix implants showed a slow tissue turnover and produced only small amounts of new bone, with no significant differences between ASA-treated and control rats. However, during the last 24 h of the study the ASA-treated implants had a significantly hampered rate of new bone formation. The tissue turnover and new bone yield, as well as the rate of new bone formation, increased in the control composite grafts but not in the ASA-treated composite grafts. Thus, the results indicate an inhibitory effect of ASA on the bone-forming capacity of bone marrow.     

Intra-rater variability in low-grade glioma segmentation

Assessment of size and growth are key radiological factors in low-grade gliomas (LGGs), both for prognostication and treatment evaluation, but the reliability of LGG-segmentation is scarcely studied. With a diffuse and invasive growth pattern, usually without contrast enhancement, these tumors can be difficult to delineate. The aim of this study was to investigate the intra-observer variability in LGG-segmentation for a radiologist without prior segmentation experience. Pre-operative 3D FLAIR images of 23 LGGs were segmented three times in the software 3D Slicer. Tumor volumes were calculated, together with the absolute and relative difference between the segmentations. To quantify the intra-rater variability, we used the Jaccard coefficient comparing both two (J2) and three (J3) segmentations as well as the Hausdorff Distance (HD). The variability measured with J2 improved significantly between the two last segmentations compared to the two first, going from 0.87 to 0.90 (p?=?0.04). Between the last two segmentations, larger tumors showed a tendency towards smaller relative volume difference (p?=?0.07), while tumors with well-defined borders had significantly less variability measured with both J2 (p?=?0.04) and HD (p?<?0.01). We found no significant relationship between variability and histological sub-types or Apparent Diffusion Coefficients (ADC). We found that the intra-rater variability can be considerable in serial LGG-segmentation, but the variability seems to decrease with experience and higher grade of border conspicuity. Our findings highlight that some criteria defining tumor borders and progression in 3D volumetric segmentation is needed, if moving from 2D to 3D assessment of size and growth of LGGs.

     

Inter-examiner variation in the assessment of age-related factors in teeth

Inter-observer variations in the registration of dental age-related characteristics have not previously been studied. Examination and registration were made by 6 dentists with varying experience in age estimation. A total of 13 age-related dental characteristics in 30 teeth extracted from adults were assessed macroscopically, by stereomicroscope and from radiographs. The measurements were analysed in a microcomputer, using the SPSS/PC+ statistical package. The results showed that, except for the score on surface roughness, significant differences were found between some of the observers for all types of measurements, when a pairedt-test analysis was made. The correlation coefficients between the observers varied and were rather weak for the surface roughness score. The study revealed systematic differences among the observers as well as differences in interpreting the definitions of the scores for the different parameters. Thus age estimation using statistical methods is seen to be dependent upon the experience of the individual observer and interpretation. Care should therefore be taken not to rely too much upon the results of an odontological age estimation. The possible implications of these results for forensic work are also discussed.